Patients seek treatment from chiropractors for osteoarthritis (OA) and Knee OA (KOA). Significant KOA impacts 10 % of individuals aged ≥63 particularly with radiographic changes; and by age 65, 80% have these x-ray changes. KOA may be the largest cause of decreased mobility, function, disability and pain in people aged ≥ 50 in the US. KOA causes 30% > age 60 to experience decreased social activities of daily living, increased cardiovascular risk, increased fall risk and secondary depression. Overall KOA prevalence is 4% in young adults, 85% in those > 75. Beyond great personal suffering - in the US, annual financial costs associated with OA were $60 billion per year in 2000 and, for all OA and rheumatic disease $128 billion in 2003. Estimates in 2005 were 27 million people suffer significantly due to OA and by 2020 in the US and other developed nations > 12 million will suffer serious, and 19 million minor to moderate work or activity related disability from OA and KOA, with the highest prevalence expected in women.